ROME/MILAN, Feb 21 (Reuters) - Italy’s competition watchdog has extended a probe into Telecom Italia to see whether the former state telephone monopoly hindered new rival Open Fiber’s efforts to roll out an ultrafast broadband network.

The regulator said it was looking into whether Telecom Italia (TIM) had tried to set wholesale prices for operators seeking broadband access that might obstruct competition.

TIM and Open Fiber, which was founded at the end of 2015, are building competing fast internet networks across Italy.

TIM, whose main shareholder is Vivendi, has previously been criticised for putting off costly upgrades to its ageing copper network to provide faster internet.

The watchdog said it would also be looking into possible anti-competitive behaviour by TIM on the retail broadband market by using privileged information it had obtained as the dominant network operator.

It said TIM’s behaviour could be part of a strategy aimed at obstructing the investment plans of Open Fiber and restricting retail ultrafast broadband competition.

TIM said in a statement it had not been involved in any anticompetitive behaviour and would continue to work with the watchdog to prove its case.

Earlier on Wednesday, a source said police had raided TIM’s headquarters in Rome as part of the antitrust inquiry.